Relative pressure field computation in human arteries based on 4D PC-MRI velocities

Obtaining vascular pressure information is of major interest for physicians since vascular diseases can be diagnosed much faster. However, complex catheter measurements are difficult to carry out and relatively time-consuming. Therefore, non-invasive techniques would significantly enhance this procedure. Using phase-contrast magnetic resonance imaging all velocity components were measured as a function of time in two neck vessels and two intracranial vessels, respectively. A script was developed that calculates the patient-specific volume flow rates through arbitrary planes within the region of interest. Afterwards, an iterative scheme based on the pressure Poisson equation was applied in order to estimate the corresponding relative pressure up to a constant defined by the user. A verification of the introduced method succeeded using 2D as well as 3D test cases from computational fluid dynamics. The calculation of the volume flow rates in the patient-specific neck vessels shows a good agreement for the considered planes and all values lie in a physiological range. Also the corresponding pressure curves appear with a realistic course. The coupling of pressure and velocity was successful and therefore relative pressure fields in the human vasculature can be calculated non-invasively. However, the accuracy of the obtained results strongly depends on the quality of the measured velocity field. Since the resolution is limited and intracranial vessels are not covered sufficiently, improvements with higher magnetic strength are needed.